The IRS has announced that the interest rates applicable to overpayments and underpayments of federal taxes are the same in the fourth quarter of 2020 as they were in the third quarter of 2020 (Rev. Rul. 2020-18). The rates are:
A tax technique for receiving a refund of back taxes by applying a deduction or credit from a current tax year to a prior tax year. For example, a business net operating loss may be carried back for two years.